dosage calculations

SopranoKris, MSN, RN, NP · Dec 29, 2014

You can buy a dosage calculation book with practice problems in it. Just search for Dosage Calculation on Amazon. The book I bought ended up being the same one we used in Pharmacology :)

Esme12, ASN, BSN, RN · Dec 29, 2014

DosageHelp.com - Helping Nursing Students Learn Dosage Calculations

Nelly_XoX · Dec 29, 2014

Check out this thread:

https://allnurses.com/general-nursing-student/the-nursing-math-264395.html

Atl-Murse · Dec 29, 2014

learned from Videos on youtube, best teaching source in my opinion. Just like your own private tutor

nurseprnRN, BSN, RN · Dec 30, 2014

All your med math questions are simple algebra word problems. All of them. That's why basic algebra is a prerequisite for nursing, not because somebody thought it would be cool to harass you with. Review your algebra book first, before you do anything else. Then refresh your chemistry on conversions-- mg to mcg, ml to l, that stuff. If you're solid on those, you're good to go.

notnursezelda · Dec 31, 2014

my basic math is great, i love algebra, but sometimes when reading some dosage calculation problems, i get tripped up.

i am subscribed to dosagehelp website, i get a problem daily through emails to work through, but some of the stuff seems more advanced than some basic algebra

thats why i thought and ask, if there is something that helps you build up on prior knowledge to the complicated stuff

and thank you for that link, Nelly!

Hailbop16 · Dec 31, 2014

Calculate with confidence is a great book.

CriticalCareRN1 · Dec 31, 2014

I absolutely love math. If nursing problems were all math problems, there would be no need to study for me, because the approach is the same each way,. I use dimensional analysis. Not that CRAZY nursing math. When you use dimensional analysis, you are actually seeing all the units, and can see the crossing off of like units. But you need to know how to set up a dimensional analysis table to start. Look at youtube videos on dimensional analysis set ups. For nursing, what ever you are looking for needs to be in the numerator, and go from there: using conversions factors to get to the desired unit, and diagonally crossing off like units. It will all make sense when you see this done on youtube. For instance, lets say you have an order that says you need to give 350mg of Tylenol, but only have on hand a 150mg tab. How many tabs do you give. So you know tab needs to be in the numerator. Therefore, 350mg times (Tab over 150mg). So the (mg) cancel out leaving the (tab) unit. Then just do your math, 350/150=2tab. That was a very simple math problem. But it works out the same each time, no matter how difficult the problem. Now, regarding reconstitution, safe dose range, and dilution scenarios, you must understand the concepts in order to work the problems. But once you understand the concepts, you can use your dimensional analysis again to get your desired units. REMEMBER, the desired unit is always in the numerator. Hope this helps ya!

nurseprnRN, BSN, RN · Dec 31, 2014

Therefore, 350mg times (Tab over 150mg). So the (mg) cancel out leaving the (tab) unit. Then just do your math, 350/150=2tab. That was a very simple math problem.
But it works out the same each time, no matter how difficult the problem. Now, regarding reconstitution, safe dose range, and dilution scenarios, you must understand the concepts in order to work the problems. But once you understand the concepts, you can use your dimensional analysis again to get your desired units. REMEMBER, the desired unit is always in the numerator. Hope this helps ya!

I'm sure this was an inadvertent error :) and that DN will be along to fix it soon. But you get the point.

As to med math being different kinds of word problems, they really aren't. The only thing that's unfamiliar about them is the words, i.e., they use names of drugs and fluids that aren't familiar to you. If you teach yourself to see through that, you will find that some of the problems are throwing a lot of extraneous information at you in an attempt to get you to use numbers that have nothing to do with the actual question being asked. For example,

Give 275mg of miraclecillin in 500cc over 30 minutes QID, using an IV set with a gtt factor of 15gtts/cc. Miraclecillin comes in vials of 1 gm. The label states, "Reconstitute with 6.5cc sterile saline for a final concentration of 100mg/cc." How many cc will your patient receive in 24 hours?

Now, they'll give you the right answer plus 3 choices that will that use all those numbers in some formula or other, but if you look carefully, all they're asking is, well, "How many cc will he get in 24 hours?" Since you'll be giving 500cc four times in 24 hours, the answer (which you can do in your head) is .... 2000cc. All that other crap is extraneous. Students get tripped up with this sort of thing all the time.

You can also read the question and change it into more familiar units. So:

If you want to eat 24 jelly beans in a minute, how many should you eat in fifteen seconds? (assuming you eat them at a regular rate of speed)

Conversely, if you eat, say, ten jelly beans in fifteen seconds, how many will you eat in a minute? (same assumption)

OR:

The physician prescribes Mandol 500 mg IM stat. The 1 Gram vial that is available has the following directions for reconstitution: Add 3 mL of an approved diluent. Provides an approximate volume of 3.5 mL. How many ml will you administer?

becomes:

"You need to get 500 jellybeans for your third grader's picnic stat! You go to the candy store, and they have bags that have 1000 jellybeans in 3 1/2 quart bags. You buy a bag. How do you know how to get 500 jellybeans out of the bag?"

500 jellybeans is half of 1000 jellybeans, so you just need to divide the total volume in the bag by 2.

OR

1.the recommended dose of cefazolin sodium for a pediatric client is 25-50 mg/kg/day, how many ml may be given daily to a 35-pound child?

You can't get an answer in milliliters if the only data you have to work in are measures of weight.

You are told how many mg of the drug is safe per each kilogram of a child's weight, and then being asked how much is an acceptable dose range for a child of a given weight. You are also asked to figure out how many kg the child weighs, when his weight is given in pounds. You need to know (or know to go look up) that 2.2 pounds = 1 kg.

For example:

It's safe to give a child one to three jellybeans every day for every kg the child weighs. The child weighs 44 pounds. How many jelly beans can he have every day?

How many kg is 44 pounds? Answer: since one kg = 2.2 pounds, 20 kg = 44 pounds.

One to three jelly beans daily is safe for each kg the child weighs, so this child can have 20 - 60 jelly beans every day.

Well, I wouldn't really give a little kid 20-60 jelly beans (even in divided doses) :eek: , but you get the idea. You are told how much drug is ok per kg, figure out the number of kg, and multiply by the acceptable dose; this gives you the acceptable total range per day. Think about what they're asking you.

CriticalCareRN1 · Dec 31, 2014

@GrnTea good catch! Supposed to be 300mg. oops!!

Nursechristensen · Jan 30, 2015

If you have an Android, you might want to try Dosage Calculation & Quiz app. The app seems to generate random questions, so you can quiz yourself on the various dosage calculation quiz questions multiple times. Interface is basic, but it does the job.